Disk files, also referred to as disk drives, are information storage devices which utilize a rotatable disk with concentric data tracks containing the information, a head or transducer for reading or writing data onto the various tracks, and an actuator connected to a carrier for the head for moving the head to the desired track and maintaining it over the track centerline during read or write operations. There are typically a plurality of disks separated by spacer rings and stacked on a hub which is rotated by a disk drive motor. A housing supports the drive motor and head actuator and surrounds the head and disk to provide a substantially sealed environment for the head-disk interface. In conventional magnetic recording disk files the head carrier is an air-bearing slider which rides on a bearing of air above the disk surface. The slider is maintained against the disk surface by a small force from a suspension which connects the slider to the actuator, so that the slider is in contact with the disk surface during start and stop operations when there is insufficient disk rotational speed to maintain the air-bearing. A lubricant is required on the disk surface to prevent damage to the head and disk during starting and stopping of the disk file.
There are several references which describe different types of head carriers and liquid-bearings as possible alternatives to the conventional air-bearing head-disk interface in magnetic recording disk files. In assignee's U.S. Pat. No. 2,969,435, a sled-type transducer carrier with a large flat surface rides on a layer of oil on the disk, the oil being supplied from an oil reservoir external to the disk file and discharged from a nozzle located ahead of the carrier. In assignee's pending application, U.S. Ser. No. 264,604, filed Oct. 31, 1988, and published May 9, 1990 as European published application EP 367510, a disk file utilizes a continuously recirculating low viscosity liquid lubricant, which is maintained as a relatively thick layer on the disk, and a transducer carrier which has triangular shaped feet to plow through the low viscosity liquid layer. The EP reference suggests that if the disk file is hermetically sealed with no air present the low vapor pressure lubricant can evaporate which allows the required recirculation of the lubricant to occur by distillation.
More recently, in assignee's co-pending applications U.S. Ser. Nos. 07/724,646 and 07/724,696, a liquid-bearing disk file and transducer carrier have been described wherein a non-recirculating high viscosity lubricant film is maintained on the disk and a transducer carrier, having specially adapted ski feet, skis on the liquid film as the disk rotates. The transducer carrier described in those applications is a modified three-rail air-bearing slider which has a forward ski foot formed on each of the outer rails and a rear ski foot formed on the center rail, the ends of the three ski feet being essentially coplanar. When the disk file reaches operating speed, the forward ski feet are raised above the liquid film due to the air-bearing effect of the slider rails, while the liquid lubricated rear ski foot skis on the liquid film.
There are several challenges facing the developers of improved liquid-bearing disk files with skiing transducer carriers. The carrier must provide a low static friction ("stiction") head-disk interface because liquid-bearing disk files generally have larger amounts of free lubricant and smoother disks than air-bearing disk files. The carrier must also be designed to minimize lubricant depletion from the disk. In addition, the carrier must be able to perform adequately over a wide range of relative carrier-disk velocities which occur at different disk radii. Thus, what is needed is a liquid-bearing disk file with an improved head-disk interface which reduces stiction, minimizes lubricant depletion from the disk, and permits the transducer carrier to ski over a wide range of velocities.